Evolution of Seismic Interpretation with Advancement in Multiple Reprocessing Efforts on a 3-D 1995 Seismic Dataset in the Monterey-Producing Santa Ynez Unit, Offshore California

The Santa Ynez Unit (SYU) is situated in federal waters in the Santa Barbara Channel, offshore California. SYU produces oil from siliceous and carbonate facies of the Miocene-aged Monterey Formation, with secondary reservoirs in deeper Oligocene to Eocene-aged sandstones. The reservoirs at SYU are located in a complex structural environment that includes normal, reverse and strike-slip faulting. Multiple reprocessing projects have resulted in step change imaging uplift. These reprocessing projects have fundamentally improved the structural and stratigraphic interpretation of this intensely faulted and folded geologic regime.

The primary producing interval at SYU is the self-sourcing Monterey Formation, a siliceous reservoir with low matrix permeability and pervasive permeable fractures. The easterly Hondo platform began oil production in 1981 while the westerly Harmony and Heritage platforms have produced since 1993.

A dual source/six streamer 3D marine survey over SYU was acquired in 1995. From 1996-2010, this dataset was reprocessed five times, each time using the most current processing and imaging algorithms. Step changes in imaging uplift were achieved from the initial 1996 Isotropic Kirchoff Time Migration to the current 2010 Anisotropic Reverse Time (RTM) Depth Migration. In addition to these primary products, other derivative volumes such as discontinuity and band-limited impedance volumes were generated to assist interpretation.

Through time, these products have provided improved imaging, enhanced depth positioning, and better geologic definition resulting in improved subsurface characterization. Despite these advances, key risks and uncertainties still exist due to the inherent limitations of the 1995 data. ExxonMobil continues to investigate a range of processing techniques to provide continued improvement of our reservoir understanding and resource management.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California